https://www.lifewire.com/how-to-calibrate-an-iphone-4172146
iPhones are prized for reliability. However, some features become less accurate or responsive over time, making it difficult to use certain apps. If your iPhone isn't working the way you expect, here are a few settings you can adjust. Most aren't necessary upkeep, like an oil change for a car. But it doesn't hurt to calibrate the settings to see if your device will work more to your liking.
If the iPhone Auto-Brightness sensor isn't working properly, the phone responds inappropriately to changes in lighting. The issue may come up because Auto-Brightness adjusts partly based on where the value was set when the feature was turned on.
Here's how to recalibrate the Auto-Brightness sensor:
Go to **General**, then tap **Accessibility**.
Select **Display Accommodations**, then turn off the **Auto-Brightness** toggle switch. Move to a dark or dimly lit room, then manually turn the **Brightness** all the way down so that the screen is as dark as possible.
To access the brightness settings from anywhere on the iPhone, swipe up from the bottom edge of the screen (or down from the top on an [iPhone X](<https://www.lifewire.com/iphone-x-4150706>)) to open the [Control Center](<https://www.lifewire.com/how-to-use-control-center-on-iphone-and-ipod-touch-4103833>).
Many apps use the iPhone motion sensor, accelerometer, and compass. When any one of these stops working properly, the iPhone recalibrates the app automatically as long as Location Services are switched on.
Here's how to make sure that your device is handling this for you:
Select **Privacy**, then tap **Location Services**.
Turn on the **Compass Calibration** and **Motion Calibration & Distance** toggle switches.
To recalibrate the Compass and motion sensor on older versions of iOS, open Compass and play the mini-game by rolling a red ball around a circle.
The iPhone battery needs to be calibrated when the phone gives inaccurate percentages. The phone may show a low percentage but last an hour or two longer. Or, it may show a full battery and shut down suddenly. Calibrate the iPhone battery to fix the way the phone monitors and reports the percentage of remaining battery power.
Leave the phone discharged and unplugged overnight to completely drain the battery.
While the phone is powered down, charge it for a couple of hours longer than is necessary to bring it to 100% capacity.
Reboot the phone, then perform a **soft reset** (also called a warm reset).